仿刺参夏眠前后池塘沉积物—水界面氮、磷通量研究

在仿刺参夏眠前后(6—10月),原位采集仿刺参养殖池塘的沉积物—水界面样品,检测沉积物上覆水的氨氮、亚硝态氮、硝态氮和无机磷酸盐含量及变化,研究沉积物—水界面氮、磷通量变化规律。试验结果显示,亚硝态氮+硝态氮(NO x - -N)通量呈先降后升的变化规律,8月的NO x - -N通量达到极低值,为-(66.12±7.66) mg/(m^( 2) ·d);氨氮(NH 4 + -N)通量呈先升后降再升高的变化规律,7月的NH 4 + -N通量达到最高值,为(6.21±0.55) mg/(m^( 2) ·d),9月达到极低值,为-(14.88± 1.44 ) mg/(m^( 2) ·d);可溶性无机磷酸盐通量呈先升后降的变化规律,8月的可溶性无机磷酸盐通量达到最高值,为( 4.20 ±0.56) mg/(m^( 2) ·d),10月达到极低值,为-(3.48±0.43) mg/(m^( 2) ·d)。相关性分析发现,可溶性无机磷酸盐通量与水温呈显著的正相关,与水体中可溶性无机磷酸盐含量呈显著负相关;NO x - -N通量与水体中亚硝态氮和硝态氮含量呈显著正相关。试验结果表明,仿刺参夏眠期间池塘沉积物是重要的氮汇和磷源,对水体的氮磷含量起着重要的调节作用。

胶州湾大沽河潮滩营养盐在沉积物—水界面的扩散通量对盐度变化的响应

2009年3、6、9和12月在胶州湾大沽河河口潮滩采集均长25cm的沉积物柱状样,利用室内培养法,培养柱状样72h。该时间段内的营养盐在水—沉积物界面的平均迁移速度视为营养盐的扩散通量。在培养中,上覆水的盐度,分别被调整到17、22和28。不同盐度水平下,氨氮和磷酸盐在沉积物—水界面的扩散通量具有明显的时空异质性;在所测试的盐度范围内,氨氮的扩散通量与盐度的相关性并不显著;而盐度对磷酸盐在沉积物—水界面的扩散具有显著的影响。在6月和9月,所有测试站位中均表现为盐度增加,磷酸盐的扩散速度下降。大沽河径流的衰减会抑制磷酸盐自沉积物向水体释放,从而导致初级生产磷的供应不足。因此,大沽河径流的降低是大沽河潮滩湿地生态功能退化的一个原因。

东巢湖沉积物—水界面氮、磷、氧迁移特征及意义

以东巢湖近城市湖湾沉积物为研究对象,在沉积物氮、磷营养盐分析的基础上,采用沉积物柱状芯样静态释放模拟法定量评估研究区域沉积物—水界面氨氮、溶解性活性磷酸盐营养盐释放潜力,利用微电极非损伤测定技术获得沉积物—水微界面溶解氧(DO)剖面分布及微界面DO消耗和扩散特征.结果表明:东巢湖近城市湖湾沉积物氮、磷污染物蓄积量较高,受TN、TP污染程度较重.沉积物内源氨氮、磷酸盐释放明显,平均释放速率分别达到32.44 mg/(m^2·d)和1.25mg/(m^2·d),区域内沉积物已成为水柱中氮、磷营养盐的污染源.研究区域上覆水体处于好氧状态,沉积物—水微界面平均DO穿透深度(OPD)达到5.3 mm,平均DO扩散通量为4.56 mmol/(m^2·d),表现出良好的DO扩散能力.沉积物内源氨氮和磷酸盐释放能力与表层沉积物TN/TP物质含量及沉积物—水微界面DO穿透深度有关,在沉积物氮、磷污染较重的情况下,DO穿透深度越低越有利于氮、磷污染物从沉积物向上覆水体释放.

3种水质调控方式下参池沉积物—水界面N、P通量的研究

为探究不同水质调控方式下仿刺参池塘沉积物—水界面N、P营养盐物质交换,采用沉积物—水界面N、P营养盐扩散通量室内培养法,研究2015年10月至2016年9月位于庄河市海参养殖基地的自然纳潮、微孔曝气(空压机0.1 kW/667 m^(2))和养水机(750 kW/h)3种不同水质调控技术下605 m×85 m参池沉积物—水界面N、P通量。试验结果显示,自然纳潮和微孔曝气池塘的NOx-通量的变化为-36.0~10.8、-12.0~7.8 mg/(m^(2)·d),且在3月、7月和8月产生了负通量,通量值于7月分别达到了全年最低[-36.0、-12.0 mg/(m^(2)·d)],而养水机池塘全年均为正值且变化为0.6~5.4 mg/(m^(2)·d);自然纳潮池塘、微孔曝气池塘NH4+通量变化为-102.6~71.4、-90.6~78.0 mg/(m^(2)·d),在7、8月均为负值,而养水机池塘全年均为正值且变化为5.4~81.6 mg/(m^(2)·d);3种参池PO43-通量全年均为正值且于7、8月达到最大,变化为自然纳潮池塘18.6~76.2 mg/(m^(2)·d)、微孔曝气池塘30.0~73.2 mg/(m^(2)·d)、养水机池塘29.4~50.4 mg/(m^(2)·d);养水机池塘沉积物—水界面N、P通量极差较另两池塘均最小。试验结果表明,养水机的作用有助于池底形成稳定氧化环境,有利于池底N、P物质释放。

主养草鱼与主养黄颡鱼池塘沉积物-水界面氮磷营养盐通量变化及与环境因子的关系

为了探讨不同主养模式池塘养殖期间沉积物—水界面氮磷营养盐通量变化特征以及与环境因子之间的相互关系,利用沉积物—水界面营养盐扩散通量的原位观测装置,分析了2013年4—10月主养草鱼和主养黄颡鱼池塘沉积物—水界面营养盐交换通量,并探讨了影响营养盐交换通量的因素。结果发现:(1)在养殖初期,各种形态氮磷在养殖池塘沉积物—水界面主要表现为从上覆水向沉积物的沉积,养殖中后期,由于温度升高以及池塘沉积物中营养物质的大量累积,各种形态氮磷表现为以沉积物向上覆水扩散为主,表明池塘沉积物是氮磷营养盐的源与汇;(2)两种不同主养模式池塘氮磷通量的统计结果表明,沉积物—水界面-N、-N和-P通量变化无显著差异,而-N、TN和TP通量有显著差异;(3)上覆水中DO含量的升高显著促进界面间-N和-N释放通量,而-N和-P释放通量与上覆水DO浓度成显著负相关;温度的升高对各种无机形态的氮磷通量有显著的促进作用。

双向环形水槽模拟变化水位和流速下洞庭湖沉积物氮释放特征

浅水湖泊生态系统中的沉积物—水界面是湖泊内源氮释放的重要界面,而水动力因素是改变沉积物氮释放的重要因素.三峡大坝修建以后,长江中下游通江湖泊的水动力条件发生了明显的变化.通过采集洞庭湖湖口区域的沉积物和水样,在双向环形水槽动力模拟装置内模拟湖泊水位和流速的变化,探讨湖泊沉积物氮在沉积物和水系统中的二次释放特征.结果表明,随着扰动强度的增加,上覆水悬浮物浓度增大,上覆水中总氮浓度增加,沉积物向上覆水释放氮的强度增强,水动力条件的改变所引起的沉积物内源氮释放不容忽视.在该模拟实验条件下,沉积物存在最适扰动水位(20cm),此水位下上覆水中悬浮物浓度最低,总氮浓度最小.水动力条件的改变对上覆水和沉积物—水界面处铵态氮和硝态氮浓度的影响并不明显,孔隙水中铵态氮与硝态氮之间发生形态的转化.

湖泊水——沉积物系统中铁—锰循环研究进展

论文基于当前湖泊水—沉积物系统中Fe、Mn的循环迁移、赋存形态以及与周围其他物质(微量重金属元素、营养盐、有机质)之间相互作用的研究,通过收集资料和归纳总结已有研究数据发现,湖泊铁一锰循环不仅受氧化还原边界层化学界面的控制,而且受沉积物一水地质界面的制约;溶解态Mn^(2+)和Fe^(2+)在水体的垂直变化是相似的,受溶解氧和H2S浓度的影响;沉积物一水界面上Fe^(2+)循环受硫酸盐还原作用抑制,而Mn^(2+)循环则激烈进行。研究和认识湖泊水—沉积物系统铁锰循环的发生机制,对淡水湖泊的水质保护和污染治理具有重要的理论和现实意义。

底栖动物降解对沉积物Co释放的影响

为了探究底栖动物降解过程中环境条件变化和钴(Co)释放机制,以太湖梅梁湾为例,采用平面光极技术测量沉积物DO的二维分布,并通过薄膜扩散梯度(DGT)技术分析了原位条件下沉积物-水界面DGT有效态重金属Co和Fe(Ⅱ)的分布及其相互关系。结果表明,底栖降解显著降低了水环境中的溶解氧,提高了上覆水及间隙水中labile-Co/Fe(Ⅱ)的浓度,labile-Co增长了486.41%(最大),降解增大了沉积物Co的释放风险;降解阶段,labile-Co与labile-Fe(Ⅱ)变化表现出高度的一致性(R^(2)≥0.433,P<0.01),表明Fe(Ⅱ)的氧化还原和S(-Ⅱ)对Fe(Ⅱ)/Co的去除作用为影响Co循环的重要因素。

Analysis of heat pulse signals determination for sediment-water interface fluxes

The heat pulse signal is analyzed in a new way with the goals of clarifying the relationships between the variables in the heat transfer problem and simplifying the procedure for calculating sediment-water interface fluxes J. Only three parameters x0 λand pc l are needed to calculate J by the heat pulse data for this analysis method.The results show that there is a curvilinear relationship between the peak temperature arrival time and sediment-water interface fluxes and there exists a simple linear relationship between sediment-water interface fluxes and the natural log of the ratio of the temperature increase downstream from the line heat source to the temperature increase upstream from the heat source.The simplicity of this relationship makes the heat pulse sensors an attractive option for measuring soil water fluxes.

Phosphorus Behavior at Sediment-Water Interface in Coastal Wetland

[Objective] The aim was to explore the role of coastal wetlands in phosphorus fixation in the Yellow River Delta.[Method] The research analyzed phosphorus behavior at sediment-water interface by static water column test. [Result] The research concluded that phosphorus concentration was in the range of 0.051-0.322 mg/L in overlying water, and phosphorus was effectively removed by degradation and adsorption. The static water column test has demonstrated that phosphorus concentration of coastal wetlands plays the role of accumulation when phosphorus concentration is lower than 7 mg/L in overlying water of coastal wetlands. It is notable that substrates of overlying water all perform well in adsorption, and the adsorption reaches saturation if the concentration goes up to 10 mg/L. [Conclusion] Coastal wetlands would significantly adsorb and degrade phosphorus in overlying water, controlling phosphorus within a lower range.

Phosphorus Fractions in Water and Sediment and Their Correlations in Hengshui Lake, China

Sediment is a principal reservoir which accumulates and releases the pollutants. It is an important way of nutrients releasing from pore water of sediments to overlying water across the sediment-water interface. Five sampling sites were selected in the Hengshui Lake. Overlying water and sediments were collected in each of them. The phosphorus fractions and their relationships were analyzed. The results showed that the change of the total phosphorus （TP） in sediment was similar to that of the total dissolved phosphorus （TDP） and soluble orthophosphate （PO4^3-） in pore water. The concentrations of PO4^3- in pore water were higher than those in overlying water, reflecting a possible diffuse trend for PO4^3-P in the five zones of Hengshui Lake. It is indicated that phosphorus and other nutrients will be transferred from sediment to pore water and then to overlying water, which can lead to lake eutrophication.

In situ measurements of benthic oxygen fluxes in Hui-quan Bay of Qingdao by eddy correlation techniques:short term pattern variations in gravel beach

The oxygen fluxe across the sediment-water interface(SWI)in coastal region is a key measure to fully understand the regulation of biogeochemical cycles in an aquatic environment.However,studies on fluxes of dissolved oxygen in gravel beach are limited,because of the difficulty in sample collection and instrumentations deployment.In this study,benthic oxygen fluxes across rocky substratum in an intertidal zone of Huiquan Bay was estimated by using noninvasive eddy correlation techniques.A total of 10 burst measurements were analyzed.The oxygen flux fluctuated from-5.7888±2.6 to+49.3344±2.6 mmol O2 m-2/d were observed.The cospectra analysis showed that the oxygen flux at the frequency band between 0.093 and 0.279 Hz(at a period from 3.58 to 10.75 s)contributed 50.19%to the total spectrum on average.The results showed that the major contribution band moved to the high frequency region gradually and reached a steady state with increasing tidal flood.It is demonstrated that wave movement and wave breaking interaction resulted in the change of oxygen flux between gravel beach and shallow waters at the start and the end of a rising tide period,respectively.The eddy correlation techniques offer an efficient means for flux measurement over a gravel or mixed sand and gravel beaches.

The mechanisms of contaminants release due to incipient motion at sediment-water interface

Sediments in many rivers and lakes are subjected to resuspension due to a combination of hydrodynamics. However, the roles of contaminant-contained dissolved and particulate sediments during the resuspension release are rarely studied. This study focuses on the release quantity of contaminants in both water phase and solid phase. Conservative tracer （NaC1） and reactive tracer （Phosphorus） were respectively added to cohesive fine-grained sediments and non-cohesive coarse-grained sediments. A range of typical shear stress was conducted to characterize the time-depended release of contaminants in a laboratory flume. When the sediment started to move, the concentration of contaminant in the overlying water increased with the bed shear stress, but the dissolved contaminants responded faster than the particulate ones. The observed contaminant release process can be divided into three main stages： the initial two hours fast mixing： the release contribution of pore water could reach up to 75%; the middle 4-6 h adsorption： the partitioning coefficient of contaminant between water phase and solid phase decreased over the time, and the adsorption of contaminates from resuspended sediment dominated the negative release; the last equilibrium stage： the desorption and adsorption reached equilibrium, and the reactive contaminant made an impact on the water quality in the solid phase. The existing formulas to evaluate the release flux are far from practice meaning as the sediment contaminants undergo a very complex release process.